الفهرس 
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Abstract
The Paleozoic Nubia as four rock units; Araba, Naqus, Abu Durba, and
Ahemir ormations. The present study deals with results of petrophysical
analyses of 51 surface plug samples were collected from the outcrops at Gebel
Abu Hasswa to represent the different lithofacies of the Nubia Sandstone units
in the eastern side of Gulf of Suze. The study area is located between Latitude
28° 20’ -28° 40’ N and Longitude 33° 10’-33° 30’ E.
The sedimentological studies that was carried out on Abu Hasswa
section samples included the petrography description and XRD analysis,
where the petrographyical study referred that all the study samples are of
quartz arenite facies, but they are different in the diageneses processes or the
compaction. The study samples were divided into four lithofacies depending
on the type and degree of cementation; the divided lithofaices are calcareous
quartz arenite, ferruginous sandstone, highly ferruginous quartz arenite, and
siliceous quartz arenite.
The XRD analysis showed that the main mineral that formed samples
is silica mineral, while the minor minerals are calcite, hematite, and kaolinite.
The correlation between thin sections and XRD results concluded that the
samples had been suffered from dissolution process that caused the oversized
porosity, in addition to, cementation process with multiple types of cements
like silica overgrowth, ferruginous, and calcite minerals.
The petrophysical evaluation of porosity and permeability of Nubia
sandstone samples were carried out for storage and flow capacity Assessment,
and to detect the degree of heterogeneity by several statistical techniques such
as Lorenz, Dykstra – parson, and Coefficient of variation. The Nubia
sandstone samples reflect good storage and flow capacity properties at some
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intervals, while in other some intervals show fair to bad storage and flow
capacity properties. This is due to the heterogeneity degree of the study
samples that can be controlled by the sedimentological and diagenetic
processes. Heterogeneity quantification was derived using Lorenz and Dykstra
parson methods where Lc = 0.23 and Vc = 0.48. These values reveal that the
Nubia sandstone samples are slightly heterogeneous.
Five hydraulic flow units (HFUs) in the study samples were derived
and identified using FZI and R35 values. HFU5 is the highest quality unit with
high porosity and permeability values, while HFU 1 is the lowest quality unit
with low porosity and permeability values. R35 values indicated that the study
samples varied from nano to mega porous units.
The next step was to study the change in the electrical properties of
Nubia sandstone rocks. In addition, linked this change to rock quality in order
to quantify the ability of the rock to transfer fluids. The different electrical
properties that were acquired are electrical resistivity, formation resistivity
factor, and tortuosity; all of the previous electrical properties were acquired
for a saturated sample of Abu Hasswa section with three solutions of different
concentrations started from 6000 ppm, passed to 30000 ppm, finally 60000
ppm.
The Nubian sandstone samples showed good relationships between the
electrical properties and porosity; especially the formation resistivity factor
with porosity that produced numerical values for a and m, where a = 2.86,
3.232, and 3.04 and m = -1.322, -1.333, and -1.318 respectively. Otherwise,
the tortuosity showed a bad relationship with porosity that may be related to
the quality of rock samples. Consequently, the concept of current zone
indicator (CZI) was used to classify the different rock samples by its quality.
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The CZI concept divided the samples into three electrical flow units (EFU) by
their electrical quality such as electrical radius index (ERI).
The produced EFUs were redrawn for tortuosity and formation
resistivity factor with porosity and permeability; where the produced values
of m were been different for EFU to another, where EFU1 has m equal -1.37,
EFU 2 has m equal -1.359, and EFU 3 has m equal -1.242.
acoustic wave properties investigation for Nubia sandstone samples of
Abu Hasswa section illustrates the relationships with different petrophysical
properties such as rock density, porosity, and permeability; and their effects
on the different elastic moduli such as bulk, rigidity, and Young’s modulus in
addition to lame’s constant and Poisson’s ratio.
The compressional and shear waves have a direct relationship with the
bulk density of rocks, which is based on porosity and cementation (iron
oxides) content. High correlation coefficients were found in the relationships
between acoustic waves and porosity and bulk density.
Several relationships were carried out as a combination between the
different elastic moduli and porosity, bulk density and acoustic velocities.
These relationships can prove the lithology of the samples as sandstone and
the high correlation coefficients make them very useful for parameters
prediction from the others.
The compressional have mean values of samples of Malha Fm, Araba
Fm, Abu Durba Fm, and Ahemir Fm are 2.76, 2.26, 3.63, and 2.28 m/sec,
while shear wave velocities have mean values of samples of Malha Fm, Araba
Fm, Abu Durba Fm, and Ahemir Fm are 1.7, 1.59, 2.37, and 1.59 m/sec/ in
addition, they showed a well correlated indirect relationships with porosity
percentage of the rock samples, moreover they were used to calculate the
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slowness, and vp/vs ratio and studied the relationships with different
petrophysical parameters.
The elastic parameters revealed that there is a significant relationship
to the nature of rocks and the diagenesis processes of the study samples,
especially the poisons ratio, where the regretted curve was started from 1.17
m/sec and -0.86 which indicate the high degree of diagenesis processes.
The intercorrelation between the different petrophysical parameters
such as porosity, permeability, grain density, resistivity, and also
compressional, and shear wave velocities was carried out using the multiregression
algorithm. The modeled petrophysical parameters showed a
significant empirical equation with good to excellent correlation coefficients.
Finally, I represent the change in the petrophysical parameters
vertically and its relationship with the rock quality, where Araba Formation
showed varied rock qualities as showed in the sedimentological part, while the
other formations showed a slight homogeneity in reservoir rock quality.